This invention relates to an improved belt tensioner device and more particularly to a belt tensioner device of the type utilized in driving a lawn mower.
Flexible drives such as belts or chains are utilized for a wide variety of purposes. These drives have particular advantage in that they permit the drive to accommodate variations in path of relative movement between the driving member and the driven member. For example, frequently flexible drives are used to drive the mower blades of a riding type lawn mower or a lawn mower attachment for a riding tractor. Flexible drives are employed for transmitting the drive from an engine driven shaft to the mower driving shaft and these shafts may be supported for rotation about non-parallel axes. In conjunction with such arrangements, the mower actually may move relative to the body of the driving vehicle as the vehicle covers the terrain to be mowed. By employing a flexible drive, such relative movement is accommodated.
However, it is desirable to insure that the tensioning on the drive belt is maintained the same regardless of the relative position of the mower and its driving engine. Therefore, various forms of belt tensioners have been employed so as to insure such tensioning. In conjunction with the belt tensioner, it is desirable that it does not maintain too high a tensioning force because of the resulting wear and shortening of the life of the belts. When such degrees of relative movement are accommodated, the tensioning force should not be too great. However, there are conditions such as abrupt acceleration, deceleration or conditions which put a load on the driving belt which can cause it to become disengaged from the pulley under these extreme conditions.
It is, therefore, a principal object of this invention to provide an improved belt tensioner which will permit a relatively low, uniform tensioning force but which will also resist the abrupt change in tensioning due to sudden changes in driving or driven loads.
It is a further object of this invention to provide a tensioner for a flexible drive that will accommodate all conditions, not place undue tension on the flexible drive, but will insure that it does not become disengaged.
It is, therefore, a still further object of this invention to provide an improved belt tensioner that can provide variable tensioning forces depending upon the conditions encountered.